Baby bottle nipples, pacifiers and other elastomeric products designed for oral use tend to wear and erode over time. Wear is accelerated by oral contact since products are chewed, gummed and acted upon by acids in the mouth. Wear of latex and elastomeric products is particularly problematic when such products are employed by infants and small children. If, for example, a baby bottle nipple becomes too worn, it may crack or break into pieces, potentially poisoning or choking the child.
Even when wear of latex products, such as nipples, is not so severe as to cause breakage, the nipple can become sticky and hard due to chemical breakdown. The nipple should be discarded in good time before breakdown of the latex occurs.
In the past, nipple wear could be assessed only by the subjective appearance of the product using relatively subjective indications such as cracking, stickiness, hardening and discoloration of the latex. These indications vary for different latex formulas. Thus, it would be desirable to provide a more positive and conclusive indicator of wear for baby bottle nipples and other latex products.
Some known methods of indicating wear on rubber, nylon and plastic products would not be completely acceptable for application to products which are suckled by infants. For example, one process of indicating wear, as disclosed in U.S. Pat. No. 4,802,255, has been utilized to indicate wear in nylon toothbrush bristles. The indicator comprises a dye that diffuses from color-impregnated brush bristles as the toothbrush is used. This process would prove unreliable as a wear indicator for latex products, since latex and other elastomers have substantially different chemical properties than nylon. Additionally, an impregnation process is not entirely suitable in products that are subjected to variable heating. A substantial source of wear in baby bottle nipples is the sterilization procedure using, for example, boiling water. Such boiling of baby bottle nipples and pacifiers would greatly accelerate the diffusion of impregnated dye. Typically, a nipple begins to degrade relatively rapidly after approximately sixty use/boiling cycles. Impregnated dye might not withstand sixty cycles before completely evacuating from the nipple. Thus, it could prove difficult to accurately gauge wear in boiled nipples using the nylon bristle wear indicator method.
In view of the disadvantages of the prior art, this invention has as one object to provide a wear indicator for an elastomeric product such as a latex baby bottle nipple that provides an accurate gauge of product deterioration while remaining safe for oral use by infants. It is a further object of this invention to provide a wear indicator that can be applied to products during manufacture and that can be formed into a variety of different shapes, colors and patterns on the product.